The present invention relates to an apparatus and method for optical inspection of pattern defects, foreign particles, and other foreign substances present on fine patterns formed on substrates through a thin-film forming process represented by a semiconductor manufacturing process or a flat-panel display manufacturing process.
A known conventional apparatus for optical defect inspection is described in Japanese Laid-Open Patent Application Publication No. Hei 08-162511 corresponding to U.S. Pat. No. 6,404,498 B1 (Patent Document 1). The apparatus described in Patent Document 1 includes: a light source capable of illuminating a sample through selection of high intensity illumination with a short wavelength interval using a Hg-Axe lamp and white light illumination using a Axe lamp, using a wavelength (e.g., 600 nm or less) selected via a wavelength selection filter, and emitting annular diffuse illumination light formed by a large number of virtual point light sources; a bright-field illumination optical system adapted to polarize annular diffuse illumination light that has been emitted from the light source via polarization conversion optical element (polarizing beam splitter and a quarter-wave plate), then condense the illumination light through the pupil of an objective lens, and irradiate onto the surface of a pattern formed on an object to be inspected with the condensed illumination light; a dark-field illumination optical system adapted to condense semiconductor laser light with a wavelength of 780 to 800 nm onto the surface of the pattern formed on the object to be inspected, and conduct dark-field illumination on the pattern; a first detection optical system adapted to condense diffracted light that includes zeroth-order diffracted light entering the pupil of the objective lens after the annular diffuse illumination light converged by and irradiated from the bright-field illumination optical system has been reflected from the pattern on the object to be inspected, then receive an image of the pattern via a bright-field image sensor after the condensed light is separated into light beams having different wavelengths via a dichroic mirror, and convert the image into an image signal of the pattern; and a second detection optical system adapted to condense scattered light that is reflected from the pattern illuminated by the dark-field illumination system and enters the pupil of the objective lens, separate the condensed light into light beams having different wavelengths via a dichroic mirror, receive, via a bright-field image sensor, the light reflected from a foreign substance, and convert the received light into a signal indicative of the foreign substance; whereby the apparatus detects defect information on the pattern and information on the foreign substance.
That is, Patent Document 1 describes that the semiconductor laser light having a wavelength of 780 to 800 nm is used as dark-field illumination light, that the white light obtained using an Xe lamp and having a wavelength of 600 nm or less is used as bright-field illumination light, and that the light having a wavelength of 600-700 nm is used as illumination light for focusing. It is also described that the first detection optical system includes an attenuation filter or a phase plate at a position conjugate to the pupil of an objective lens.
Also, Japanese Laid-Open Patent Application Publication No. 2004-87820 (Patent Document 2) discloses a method and system for retrieving and referring to past inspection parameter data on similar types of semiconductor components and setting new inspection parameters.